The present invention relates generally to a machine for cleaning articles, more particularly to a machine having a system for reducing the amount of energy and water consumed during an operation cycle.
Reducing the amount of energy and water consumption in appliances such as dishwashers or clothes washers, is a significant problem, in part because a large amount of energy is needed to heat incoming water. For example, dishwashers use energy from two distinct sources. One source is the water-heating energy (WHE) consumed by the hot water heater that supplies hot water to the dishwasher. The second source is the electrical energy used to run the dishwasher pump and a resistance heating element enclosed in the dishwasher. The resistance heating element boosts the water temperature during wash and dries the dishes after they are clean.
The Department of Energy (DOE) requires manufacturers to measure the mechanical energy consumed by the motor and heating element with a kilowatt-hour meter and the quantity of water used with a flow meter and timer. The total energy consumption per cycle is defined as E=WHE+M, where WHE is the water heating energy used by the hot water heater to supply hot water to the dishwasher and M is the mechanical energy consumed by the motor and heating element, that is measured with the kilowatt-hour meter. Incoming 120xc2x0 F. hot water is assumed to be provided from a 50xc2x0 F. cold source with a constant volumetric specific heat (Cv) of Cv=0.00240 kwh/gal- xc2x0 F. The xe2x80x9cNormalxe2x80x9d cycle of a typical dishwasher uses a volume (V) of water for an entire cycle of V=9.1 gallons.
The equation for Water Heating Energy (WHE) is WHE V Cv (T2xe2x88x92T1), where T2 is the temperature of the heated water and T1 is the temperature of the water from the cold source. Therefore, the WHE for one cycle is 9.1 galxc3x970.0024 kwh/gal- Fxc3x9770 F=1.5288 kwh of water heating energy. The average mechanical energy consumption per cycle runs about 0.65 kwh. From Equation 1, the average total energy consumption for a xe2x80x9cNormalxe2x80x9d cycle is 2.1768 kwh. Therefore, reducing the water heating energy by reducing the water consumption has a major impact on the overall energy consumption of the dishwasher.
As stated above, the DOE energy rating for the dishwashers is based primarily on the amount of hot water consumed to complete the washing of one load. Most dishwashers presently require about 9.1 gallons of hot water per load. Each load requires about six (6) fills of fresh hot water, about 1.4 to about 1.9 gallons of hot water per fill. The first two fills are needed for the prewash cycles, followed by a fresh fill for the main wash cycles. The last three fills are needed for the two post rinse and one final rinse cycle. Based on six (6) fills (9.1 gallons of water), the DOE rating is about $59.00.
Prior efforts to recycle hot water from one fill to the next have usually involved the use of a screen (coarse or fine) and the use of a centrifuge to separate the soils. The screens often need to be removed and cleaned to prevent bacteria growth, and are, thus, inefficient and impractical. The centrifuge is efficient, but it has to be rotating at all times to provide efficient separation, which requires energy and the moving parts require more space and more maintenance.
Therefore, it is apparent from above that there exists a need in the art for reducing the energy consumption during wash loads of cleaning machines, such as dishwashers. Such systems and methods should at least partially recycle the water during a fill or reuse at least a portion of the same hot water from one cycle to another, thereby, achieving significant energy saving. For the hot water to be recycled or reused, it has to be separated from particles and any suspended or dissolved solids. It is a purpose of this invention, to fulfill these and other needs in the art in a manner more apparent to the skilled artisan once given the following disclosure.
In accordance with this invention, a cleaning apparatus includes a hydroclone for at least partially recycling hot water used in a cleaning apparatus. One embodiment of the invention disclosed herein is in the form of a dishwasher.
The appliance comprises a container for receiving the soiled articles, a circulation pump for distributing a hot liquid to the container, a drain positioned in the container and connected to the pump for emptying the liquid from the container upon completion of a cycle and a hydroclone connected to the drain and the pump, for removing soil from the liquid such that about ninety percent (90%) of the liquid distributed to the container during one cycle can be utilized during at least one subsequent cycle.
Another embodiment includes a dishwasher having a normal operating cycle, the dishwasher comprising a container for accommodating a plurality of articles, a circulation pump for delivering a liquid to the container and for circulating the liquid within the container, a diverter connected to the circulation pump for diverting at least a portion of the circulating liquid to a hydroclone while returning at least about ninety percent (90%) of the liquid diverted to the hydroclone to the circulating liquid, the returned liquid having at most about 0.02% solids contained therein.